Sheet bending brakes generally comprise an elongated bottom member carried in a fixed position on a frame and having an upper clamping surface; an elongated top member with a lower clamping surface, the top member being vertically movable on the frame toward and away from the bottom member for clamping sheet material between the clamping surfaces and having a bending anvil along a front edge; and an elongated bending member mounted beneath a front edge of the bottom member and pivotal upwardly to bend clamped sheet material (typically sheet metal) over the bending anvil. The frame typically comprises an interconnected series of flattened C-shaped members that open frontward and hold the top and bottom members at corresponding top and bottom lips of the C-shape. Sheet bending brakes of this character are well known, and many are designed to be portable so that they can be transported for use at temporary work sites, typically to be set up on sawhorses or the like. Therefore such brakes must be rugged, and any accessories must likewise be rugged and also capable of being quickly and easily assembled and disassembled if the accessories protrude from the main body of the brake.
Present sheet bending brakes are generally available with member lengths from 6.5–14.5 feet, for example. An approximately U-shaped handle is typically provided on top for actuating the clamping/unclamping action of the top member. Similarly, a pair of straight rods, or more typically a U-shaped handle, hangs downward from the bending member such that an operator can reach down, grasp the handle, and pivotingly lift it to bend clamped sheet material over the bending anvil. The sheet material is commonly 24″ wide, possibly supplied from a coil or roll, and as a “workpiece” the sheet material extends forward out away from the top and bottom clamping members. A single operator must align a desired bending line of the sheet material (workpiece) with the bending anvil, then both support and hold in position the sheet material with one hand while reaching over to close the clamp. Then the operator must reach down and pull up the bending member handle, possibly while still supporting the sheet material with one hand. Therefore, a problem associated with conventional sheet bending brakes is providing support for the sheet material extending in front of the brake. Particularly for longer pieces of sheet material, an assistant to the operator may be needed, but of course this adds to labor costs.
Another problem associated with conventional sheet bending brakes lies in squaring sheet material with respect to the bending anvil as the sheet material is inserted into the brake. That is, it is generally desired that bends or cuts in the sheet material made with the assistance of the sheet bending brake be square and parallel to an edge of the sheet material and to each other. Making the cuts or bends square to the material edge can be a time-consuming operation, resulting in undesirable expense and scrap.
Another problem with conventional sheet bending brakes is the labor and expense associated with formation of compound bends (including hems) in the sheet material when forming building trim elements and the like. For example, it is conventional practice to employ a ruler or scale to make marks at the ends of a length of sheet material, and to use these opposed marks in an effort not only to square the sheet material in the bending brake but also to locate the positions of the desired bends or cuts. For compound bends, marks may need to be made on both sides of the sheet. Another conventional technique is to employ a small strip of material, such as scrap material, to form the desired contour or profile of the trim element, including multiple bends and hems as desired. When the strip has been bent to a satisfactory contour, it is then flattened again in such a way that the stresses imparted to the strip material at each bend are plainly visible as marks on the flattened strip, thereby generating a “template strip”. The template strip is then placed in turn along each end of the sheet of material to be contoured, and manual cutters or snips are used to mark the longitudinally spaced material ends at lateral positions at which the material sheet is to be bent or cut. After the sheet is bent and cut, the ends having the snip marks usually must be trimmed off. It is self evident that this is a time-consuming and expensive operation that undesirably increases the costs of building construction.
Another problem with conventional sheet bending brakes is encountered in work situations that call for “mass production”, i.e., making the same bend or set of compound bends in multiple pieces of sheet material. Easily adjustable and accurately settable gauges and other aids or accessories could significantly improve an operator's efficiency in such situations.
U.S. Pat. No. 6,082,164 (Palmer; 2000) discloses a method and apparatus for supporting and positioning a workpiece in relation to a machine, the disclosed machine embodiment being a sheet bending brake. The apparatus includes an edge guide against which an edge of the workpiece is placed; and a horizontally swinging support structure for supporting the edge guide for swinging movement in a plane to adjust the edge guide's distance from the machine, and for maintaining the edge guide in a generally parallel orientation relative to the machine as the edge guide is swung to and from the machine. The method includes placing the edge of the workpiece against the edge guide so that the workpiece is in the parallel orientation relative to the machine; and swinging the edge guide to adjust its distance from the machine so that the workpiece will be in a desired position relative to the machine when the workpiece's edge is against the edge guide. The apparatus is attached to the front of the bending member, and is collapsed against the bending member before the bending member is lifted. As disclosed, the support structure is mounted at a lower elevation than the clamping surface, therefore an auxiliary elongate member (66) is swingingly secured to the first elongate member in order to provide an elevated guiding surface (74). The '164 apparatus does not appear to provide a scale for measuring workpiece width, and the support structure cannot be fixed at a predetermined workpiece width for duplicating widths on multiple workpieces. Although the description briefly discusses providing an edge guide with a different, predetermined but non-parallel orientation relative to the brake, it is not disclosed how this would be implemented, and whether the non-parallel angle could be easily changed to different, known angles as desired.
U.S. Pat. No. 5,761,939 (Spencer et al.; 1998) discloses an automatic indexer for a sheet bending brake (30), wherein the indexer (e.g., 62) functions to square sheet material with respect to the bending anvil (46) as the sheet material is inserted into the brake between top and bottom members (38, 42), and to measure (gauge or index) the amount of material inserted into the brake with respect to the anvil edge. The indexer is a “back gauge”, being fixedly mounted inside the brake, i.e., behind the top and bottom members, preferably being affixed to one or more C-shaped members (e.g., 34). Two functionally equivalent indexer embodiments are disclosed: a first indexer (62) is adapted to be assembled as a permanent part of a sheet bending brake (30) at the time of original manufacture, whereas a second indexer (100) is adapted to be provided as a separate construction for mounting to a sheet bending brake (30) as an add-on in the aftermarket. The indexer (e.g., 62) includes a pair of slides (e.g., 76) having means for mounting the slides parallel to each other and spaced from each other lengthwise of the clamping surface on the bending brake. A pair of carriages (e.g., 78) are each slidably disposed on one of the slides, and a bar (e.g., 84) extends longitudinally between the carriages and parallel to the clamping surface for engagement with an edge of sheet material inserted between the top and bottom members of the sheet bending brake. The carriages are resiliently biased (e.g., springs 80) toward the clamping surface of the sheet bending brake, and means are coupled to the carriages for relating distance between the anvil to the edge of sheet material in engagement with the bar. This distance is either a direct measure to the edge of the anvil for forming indexed bends, or an offset distance with respect to the anvil for indexing the sheet material for a cut employing a manual slitter that cuts the material at a predetermined offset distance from the anvil edge. Thus, the indexer automatically squares the cut or bend to the edge in engagement with the indexer, and automatically positions the bend or cut with respect to the anvil edge as controlled by the indexer. In a first embodiment, the indexer (66) includes a bracket (90) that extends laterally from each carriage (78) over lateral slots (72, 74) in which are placed a scale (92) and optionally a template strip (98′), such that an edge of each bracket (90) may be employed in conjunction with the scale and/or template strip for indexing sheet material workpieces for cutting or bending. At least one carriage (78) has a lateral opening that receives a threaded shaft coupled to a handle (96) that may be rotated to bring the threaded shaft into engagement with the slide rod (76) for locking the carriage in position.
It can be seen that the indexer (back gauge) of Spencer et al. '939 has various problems. The scale is hard to read inside the brake, particularly for an operator standing on the other side of a wide piece of sheet material. For like reasons, the handle locking the carriage in position is awkward and/or difficult to use, therefore the spring biasing must be pressed against by the sheet material while the clamping members are clamped on the material. If thinner sheet material is being used, then the material will buckle, leading to inaccuracies in measurement by the indexer. Finally, additional means must be provided if support is desired for the sheet material extending out in front of the brake.
Thus there is a need for a scale/gauge/indexer that extends forward from the brake (i.e., a “front gauge”), preferably one that provides support for the workpiece, that does not put spring force on the workpiece, and is otherwise simple and efficient for one-operator usage. A further problem that must be addressed by any front gauge is how to avoid interfering with the bending of the workpiece by the upward-pivoting bending member.
The J-Dan Company of Romulus, Mich. presently offers a front mounted gauge that is sold under the trademarks of TRADESMEN™ Quick-Gauge™ and described in their sales literature (see their website wwwj-dan.com) as having “U.S. and Foreign patents pending”. As best as can be determined from the photographs and text in their literature, the Quick-Gauge™ front gauge comprises a pair of gauges that hook onto the outside front of a Tradesmen™ brake's top jaw. Two “tape measure” scales are visible on top of each gauge (one for cutting and one for bending, etc.), and an adjustable stop with a thumbscrew style of set screw slides in-out over the scales for gauging predetermined widths of sheet material. It can be seen that the sheet material must be held up under the gauge(s) while the brake is clamped on the sheet material, and then the gauge(s) must be removed before the material can be cut or bent upward. Apparent problems include the following. Since the stop is not very wide, two gauges must be employed in order to assure squaring the material to the brake. If an operator is holding the material up against two gauges, then an assistant may be needed to provide a third hand for clamping the brake. When relatively thin and wide sheet material is being gauged, the material will tend to sag under its own weight, leading to inaccurate gauging. Similarly, if the operator pushes upward too hard while supporting the sheet material, then the gauge(s) can be lifted up, also leading to inaccurate gauging. Finally, the forgoing problems combined with the inconvenience of removing and re-applying the gauges for each bend or cut contribute to significant inefficiency of operation as well as a disincentive for use of the Quick-Gauge™ front gauge(s).
Concerning accessories for sheet bending brakes, U.S. Pat. No. 4,512,174 (Rhoades; 1985) discloses a combined sheet bending brake and platform wherein the platform is for supporting a set-aside piece of sheet material without interfering with the operation of the brake on another piece. The platform (60) comprises a tubular bar that is U-shaped and has spaced arms (61) connected by cross-portion (62). The free end of each arm extends through longitudinally-spaced openings (63, 64) in a rear rail (16) portion of the brake's frame. The arms are telescopically received in the rear rail so that the platform can be stored by shifting the arms so that they extend within the confines of the front and rear rails of the frame. The platform can be extended by pulling outwardly (rearward). Locking pins (67) fitted into holes in the arms are provided to hold the platform in, extended or retracted. Also mentioned is an “adjustable stop” (53) comprised of a flange (42) on a track receiving a C-shaped portion (54) having a downwardly extending portion (56) such that the stop can be moved along the track and held in position by a thumb screw (55), thereby providing a stop for adjusting a sheet in proper position for bending. There is no mention of a scale for the disclosed back stop that therefore appears to be an elementary form of back gauge.
A forward extending support is offered by the Tapco Products Company (Plymouth, Mich.) as seen in their 2003 Integrated Tool Systems Full Product Line Catalog. The “Port-O-Bender® Table” is a removable accessory table for added accuracy and support with heavy metals. As best as can be determined from the catalog photographs, the table is a relatively small, flat, unmarked rectangular surface that is mounted out in front of the bending member such that the long axis of the rectangle extends longitudinally. The table is mounted on an L-shaped support bracket wherein the long leg of the “L” is horizontal and extends outward from underneath the brake, and the short leg rises upward to hold up the table. The long leg is removably attached under the brake by two hooks apparently sliding on the long leg: one hook being rear-opening for sliding rearward to hook up and around a rear frame rail; and the other hook being front-opening for sliding frontward to hook up and around a front frame rail of the brake. Manual positioning of the sliding hooks provides arbitrary outward positioning of the table such that a cutter can pass between the table and the front of the brake.
Other prior art includes the following.
U.S. Pat. No. 5,661,996 (Welty; 1997) discloses a back gage for a bending brake. The back gauge broadly comprises a movable carriage assembly arranged on the bed of the bending brake, a motorized drive assembly for moving the carriage assembly relative to the brake edge of the bending brake, and a measuring device (e.g., a retractable tape measure or a digital readout) mounted to the bed of the bending brake and coupled to the movable carriage assembly. The Welty '996 back gage appears to be most suitable for heavier, fixed-location brakes such as those generally used in machine shops.
Other manually adjusted back gauges are disclosed in U.S. Pat. No. 873,358 (Emrich; 1907), U.S. Pat. No. 627,309 (Reese; 1899), U.S. Pat. No. 404,164 (Buckman; 1889), and U.S. Pat. No. 366,486 (Kimmel; 1887). They all suffer the limitations of back gauges discussed hereinabove.
Thus there is a need for an easy-to-use gauge for a sheet bending brake that avoids the problems and limitations of the prior art. It is an object of the present invention to provide a front gauge that squares and supports a workpiece while establishing an easily settable gauge of workpiece width to the bend point. It is a further object to provide a front gauge that does not apply force to the workpiece while it is being gauged. It is a further object to provide a front gauge that conveniently avoids interfering with operation of the bending member and its activating handle or handles. It is a further object to provide a front gauge that can be easily removed and accurately re-applied to enhance portability of the bending brake. It is a further object to provide a front gauge that is universally adaptable for mounting (preferably removable mounting) on the majority of commercially available bending brakes. It is a further object to provide additional features and accessories that significantly improve an operator's efficiency in mass production situations involving repeated bends in multiple workpieces. Other objects of the invention may become apparent in light of the following description.